The present invention relates to an optical storage apparatus using an exchangeable medium such as CD, MO cartridge, or the like and, more particularly, to an optical storage apparatus for variably controlling a medium rotational speed for a constant linear velocity (CLV) and simultaneously correcting an eccentricity by using an eccentricity memory when a CD is reproduced.
Attention is paid to an optical disk as a storage medium as a center of multimedia which has rapidly been developing in recent years. For example, as for an MO cartridge of 3.5 inches, in addition to conventional MO cartridges of 128 MB and 230 MB, media of a high density recording such as MO cartridges of 540 MB and 640 MB and, further, a medium of a direct overwriting type are also being provided in recent years. As an optical disk drive, therefore, it is desirable that various media of 128 MB, 230 MB, 540 MB, and 640 MB, and further of the direct overwriting type which can be obtained at present can be used. In recent years, in personal computers which have rapidly been spread, a function for reproducing a compact disc (CD) which is known as a read only disk is indispensable. It is difficult to mount an optical disk drive of an MO cartridge as an exchangeable optical disk drive in addition to an optical disk drive for a CD from a viewpoint of a space and costs. In recent years, therefore, an optical disk drive which can use both of the MO cartridge and the CD has also been developed. According to the optical disk drive of the CD/MO compatible type, with respect to an optical system, a mechanism structure, and a controller circuit unit, a common use for both of a CD and an MO cartridge is realized as much as possible. Further, in recent years, a digital video disk (DVD) is also started to be spread and a common use for both of a DVD and an MO cartridge is also realized as much as possible in a manner similar to the CD.